install/0000_99_machine-api-operator_00_tombstones: Drop obsolete file

Since these manifests took effect in af2f3bd (add cvo ha
annotations to tombstones, 2021-07-29, openshift#893, OpenShift 4.9), the only
change has been d3a5a0e (add capability annotation, 2023-02-14, openshift#1119).
We can remove these deletion references now, because a 4.8 cluster that
might have included these resources should have completed an update to
4.9 which would have removed them.  And if that failed, they should
have completed an update to one of the later 4.y and removed the
resources.  By removing the resource, we save the cluster-version
operator some time checking to ensure deletion, and only expose
ourselves to leaking the resources on clusters that updated from 4.8
through to 4.14 without ever having completed an update before
reaching 4.14.